ROBERT, Genevieve¹, WHITTINGTON, Alan G.¹, STECHERN, André², and BEHRENS, Harald², (1) Department of Geological Sciences, University of Missouri-Columbia, 101 Geology Building, Columbia, MO 65211, genevieve.robert@mail.missouri.edu, (2) Institut für Mineralogie, Universität Hannover, Callinstraße 3, Hannover, D-30167, Germany